Problem: Simplify the expression. $(5z+5)(2z+1)$
Answer: First distribute the ${5z+5}$ onto the ${2z}$ and ${1}$ $ = {2z}({5z+5}) + {1}({5z+5})$ Then distribute the ${2z}.$ $ = ({2z} \times {5z}) + ({2z} \times {5}) + {1}({5z+5})$ $ = 10z^{2} + 10z + {1}({5z+5})$ Then distribute the ${1}$ $ = 10z^{2} + 10z + ({1} \times {5z}) + ({1} \times {5})$ $ = 10z^{2} + 10z + 5z + 5$ Finally, combine the $x$ terms. $ = 10z^{2} + 15z + 5$